The drag on a submarine moving below the free surface is to be determined by a test on a 1/19-scale model in a water tunnel. Th e velocity of the prototype in seawater (ρ = 1015 kg/m³, v = 1.4 × 10^–6 m²/s) is 1 m/s. The test is done in fresh water at 20°C. Determine the speed of the water in the water tunnel for dynamic similitude and the ratio of the drag force on the model to the drag force on the prototype.